QRPer Notes: Alan Reviews the FX-4C, Common Mode Chokes, and Kitchener Waterloo ARC Hamfest Tour

Because I receive so many tips from readers here on QRPer, I wanted way to share them in a concise newsletter format.  To that end, welcome to QRPer Notes, a collection of links to interesting stories and tips making waves in the world of radio!

Radio Review: FX-4C SDR QRP Transceiver

Many thanks to Ron who shares this excellent review of the FX-4C by our friend Alan (W2AEW):

Click here to view on YouTube.

Common Mode Chokes

Many thanks to David (WK4DS) who shares the following post about common mode chokes.

Click here to read.

Kitchener Waterloo ARC Hamfest 2023

Many thanks to John (VE3IPS) who shares his quick video tour of the Kitchener Waterloo ARC Hamfest:

Click here to view on YouTube.

4 thoughts on “QRPer Notes: Alan Reviews the FX-4C, Common Mode Chokes, and Kitchener Waterloo ARC Hamfest Tour”

  1. The FX-4c discontinued.


    FX-4CR Pre-order Available
    We are initiating another production run, expected to arrive in June. Get your order in now.

    HF SDR with Bluetooth audio connection for wireless digital operation, 80/60/40/30/20/17/15/12/10m and 6m TX and RX. 15-20w TX on HF and 5w on 6m. Built-in sound card. 48 kHz spectrum waterfall display. High quality machined aluminum case.

    Place Order

    HF SDR with 80/60/40/30/20/17/15/12/10m and 6m TX and RX. 5w TX power on all bands. Built-in sound card. 48 kHz spectrum waterfall display. Light-weight extruded aluminum case with room for user-added battery or ATU.

  2. As for common mode chokes, my reference design is the one from Rick (DJ0IP)


    then, willing to further fathom chokes and core materials, here is a good reference


    that being said, in my very humble opinion, that #43 toroid had far too many turns, winding a bit less would probably be a better idea, and then, to flatten the 10m response, one may add a capacitor across the wiring, a 120pF or so may be a good starting point

    1. Yes, so many turns increases the choking effectiveness, but reduces the frequency range over which it works well:

      A trick for new hams. If you can’t terminate coax, and especially if you want PL-259s, you may have trouble getting them through the hole more than a few times as the coax starts to fill the space. If you get it pre-terminated with a SMA connector on one end, and use an adapter, that won’t be an issue. SMAs are teeny, and very low loss. Adapters will have a little loss, but usually not worth noting. As a result, you can build this type of choke with zero tools. It also makes it possible to disassemble later, in case you want to change the number of turns or build something different.

  3. I have a FX4CR radio and have two questions:
    1. what do you find is the optimum mic gain setting for SSB voice?
    (Using the factory mic).
    3. Have you had any success using JS8Call and this transceiver?
    I cannot get it to work with my M1 Mac.

    Thanks in advance.
    Bart AF7JL

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